This invention relates to deep well pumps of the type widely used for production of oil from deeper wells. A conventional fluid operated deep well pump is shown in U.S. Pat. No. 2,081,223, and the present invention is an improvement on the pump shown in that patent.
A typical deep well pump has a fluid powered motor and a fluid pump with the motor piston and the pump piston in axial alignment on a piston rod.
A typical pump is in the order of 1.9 to 3.8 inches diameter and 6.5 to 25 feet long, and is positioned in the bottom hole assembly of the well casing. The outside diameter of the bottom hole assembly typically is in the order of 4 to 8 inches and the inside diameter of the well casing typically is in the order of 41/2 to 9 inches. The pump as shown in the U.S. Pat. No. 2,081,223 has a single annular seal between the pump and the bottom hole assembly adjacent the upper end of the pump.
A pump must be removed from the well periodically for repair, including replacement of seals. The life of the pump in the field depends upon a number of factors including the nature of the fluid being handled and the operating speed.
In order to obtain more pumping power, especially for operation at greater depths, multi-engine pumps have been produced, and a typical example is shown in U.S. Pat. No. 3,653,786. In this design, two fluid powered motors are positioned one above the other with the motor pistons on the common piston rod. This dual engine configuration requires porting to the exterior of the pump to provide fluid paths around various components, resulting in a larger diameter well casing requirement thereby increasing the expense of the installation, or in a reduced diameter for the pump with a reduction in production. Also, additional annular seals are required on the exterior of the pump for the externally ported flow paths. These additional seals increase the costs of construction and of maintenance of the pumps.
Accordingly, it is an object of the present invention to provide a new and improved deep well pump having two fluid powered motors with the motor construction contained within the pump without requiring any external porting and without requiring any additional external seals.
Another object of the invention is to provide a multi-engine pump which can be used in deeper wells while using the same surface power fluid pressure and the same well casing diameter as are used with present day single engine pumps.
A specific object of the invention is to provide such a multi-engine pump which operates with internal porting and internal concentric fluid flow paths and which can easily be adapted to existing bottom hole assemblies of appropriate length.
In particular, it is an object of the invention to provide such a deep well pump configuration which can be utilized with one fluid pump or with a plurality of fluid pumps and which can be used with open power fluid path pumps and closed power fluid path pumps. The invention is not limited to a pump with two fluid powered motors, and three or more motors could be utilized. However present day design considerations indicate that the invention will most likely be utilized with only two motors.
Other objects, advantages, features and results will more fully appear in the course of the following description.